Siblings Sidney and Stella do everything together — feed the ducks, play games, read, share a room (that’s sternly divided with a dotted white line) — with one exception. They don’t share.

Imagine! Two small children who don’t share! Well, suspend disbelief. So Stella and Simon are arguing over a ball — a very bouncy ball that is also so hard that it’s capable of shattering the moon (but not, for some reason, whatever it touches in their house). And as they argue, they grapple with the ball until it slips loose and bounces all the way to the (apparently fragile) moon, and the “moon broke into a million pieces.”

Chaos ensues, although not the horrific kind that Susan Beth Pfeffer imagines in her excellent Survivors books about another moon-related catastrophe.

There is confusion, sure. There are opportunists who sell Moon ice cream, and Moon balloons, and other souvenirs. (But not a peep about what happens to the ocean tides, or the planting cycle, or that sort of thing.)

Faced with creating a worldwide shortage of The Moon, Sidney and Stella are forced to cooperate. Their solution is even unlikelier than self-regenerating fossil fuel, but reasonably satisfying to the very young readers that author Yarlett is targeting.